40 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Milton | 1 | 121,540 | 120,054 | 0.71% | 3,530 | 34 | Township |
| Pittsfield | 2 | 3,985 | 4,173 | -0.77% | 833 | 5 | City |
| Pittsfield | 3 | 3,842 | 4,015 | -0.72% | 102 | 38 | Township |
| Barry | 4 | 1,527 | 1,600 | -0.78% | 40 | 39 | Township |
| Barry | 5 | 1,232 | 1,294 | -0.81% | 860 | 1 | City |
| Griggsville | 6 | 1,225 | 1,292 | -0.89% | 33 | 38 | Township |
| Pleasant Hill | 7 | 1,179 | 1,209 | -0.25% | 31 | 38 | Township |
| Griggsville | 8 | 1,031 | 1,091 | -0.96% | 932 | 1 | City |
| Newburg | 9 | 917 | 956 | -0.65% | 25 | 37 | Township |
| Pleasant Hill | 10 | 895 | 924 | -0.56% | 1,170 | 1 | Village |
| Kinderhook | 11 | 699 | 730 | -0.71% | 18 | 38 | Township |
| Pleasant Vale | 12 | 490 | 503 | -0.2% | 13 | 39 | Township |
| New Salem | 13 | 479 | 495 | -0.42% | 13 | 38 | Township |
| Perry | 14 | 469 | 485 | -0.42% | 13 | 37 | Township |
| Spring Creek | 15 | 455 | 471 | -0.66% | 12 | 37 | Township |
| Montezuma | 16 | 437 | 444 | 0% | 13 | 34 | Township |
| Atlas | 17 | 430 | 447 | -0.69% | 7 | 64 | Township |
| Martinsburg | 18 | 369 | 374 | 0% | 10 | 38 | Township |
| Hull | 19 | 366 | 387 | -0.81% | 201 | 2 | Village |
| New Salem | 20 | 329 | 344 | -1.2% | 9 | 36 | Township |
| New Canton | 21 | 320 | 331 | -0.62% | 363 | 1 | Town |
| Perry | 22 | 301 | 313 | -0.66% | 780 | 0 | Village |
| Nebo | 23 | 269 | 277 | -0.37% | 620 | 0 | Village |
| Hadley | 24 | 243 | 250 | -0.41% | 7 | 37 | Township |
| Detroit | 25 | 239 | 243 | 0% | 9 | 26 | Township |
| Derry | 26 | 208 | 214 | -0.48% | 6 | 37 | Township |
| Milton | 27 | 205 | 208 | 0% | 531 | 0 | Village |
| Pearl | 28 | 196 | 198 | 0% | 8 | 25 | Township |
| Kinderhook | 29 | 181 | 187 | -0.55% | 224 | 1 | Village |
| Baylis | 30 | 163 | 169 | -0.61% | 346 | 0 | Village |
| Chambersburg | 31 | 134 | 136 | 0% | 5 | 29 | Township |
| New Salem | 32 | 114 | 120 | -0.87% | 109 | 1 | Village |
| Pearl | 33 | 104 | 106 | 0% | 69 | 2 | Village |
| Flint | 34 | 95 | 94 | 0% | 6 | 15 | Township |
| Detroit | 35 | 74 | 74 | 0% | 295 | 0 | Village |
| Ross | 36 | 51 | 53 | 0% | 2 | 27 | Township |
| Levee | 37 | 50 | 52 | 0% | 2 | 22 | Township |
| Cincinnati | 38 | 22 | 23 | 0% | 1 | 24 | Township |
| Florence | 39 | 16 | 18 | 0% | 58 | 0 | Village |
| Valley City | 40 | 15 | 14 | 0% | 56 | 0 | Village |
Milton is the largest city in Pike County, with a population of 121,540.
Valley City is the smallest city in Pike County, with a population of 15.
There are 40 cities in Pike County, Illinois.